Characterization of simple polyphenols in seeds of autochthonous grapevine varieties grown in Croatia (Vitis vinifera L.)

Abstract

Context and purpose of the study – Croatia has rich grapevine genetic resources with more than 125 autochthonous varieties preserved. Coastal region of Croatia, Dalmatia, is well known for wine production based on autochthonous grapevine varieties. Nevertheless, only couple of these are widely cultivated and have greater economic importance. Grape seeds are sources of polyphenols which play an important role in organoleptic and nutritional value of grape and wine. Hence, the aim of this study was to evaluate the simple polyphenols from grape seeds in 20 rare autochthonous grapevine varieties.

Material and methods – Samples were collected during two consecutive years (2011. and 2012.) from germplasm collection in Split (Dalmatia). Grape samples were constituted of five bunches of fully ripe grapes. Seeds were manually separated, freeze-dried, grounded and stored at a low temperature until analyses. Polyphenolic compounds were analysed using HPLC analysis.

Results – Eight polyphenolic compounds, galic acid, monomeric flavan-3-ols (catechin, epicatechin, gallocatechin and epicatechin 3-O-gallate) and procyanidin dimers (B1, B2 and B4) were detected. According to the investigated polyphenolic compounds significant differences between investigated varieties were found. Gallic acid content ranged from 91.0 to 245.08 total monomeric flavan-3-ols from 619.2 to 13539.6 mg kg-1 and total procyanidin dimers from 975.3 to 4140.2 mg kg-1 of seed. Catechin (263.2 to 8124.2 mg kg-1 seed) was found as main monomeric flavan-3-ol, epicatechin 3-O-gallate, gallocatchin and epicatechin varied between 0-164.31, 37.19-155.07 and 277.5-5224.4 mg kg-1 seed, respectively. Procyanidin B2 (420.2 to 2207.8 mg kg-1 seed) was found as a main procyanidin dimer. Procyanidin B1 and B4 amount varied between 401.80-165.19 and 276,7-1539.4 mg kg-1 seed, respectively. Gegić had lowest and varieties Plavac mali and Babić highest amount of all investigated polyphenolic compounds. This study presents the first evaluation of Croatian grapevine varieties by characterization of seed polyphenolic compounds and it shows huge variability among them. More detailed analysis of polyphenolic compounds in selected varieties are carry out in our further research activities.